U.S. patent number 6,725,850 [Application Number 10/350,035] was granted by the patent office on 2004-04-27 for gas-liquid separation device in a vibrator engine.
This patent grant is currently assigned to Fuji Jukogyo Kabushiki Kaisha. Invention is credited to Masaaki Higuchi, Shigeatsu Hongo, Satoshi Ishida, Ryoji Kurasawa.
United States Patent |
6,725,850 |
Kurasawa , et al. |
April 27, 2004 |
Gas-liquid separation device in a vibrator engine
Abstract
In a gas-liquid separation device in a vibrator engine according
to the present invention, a crank chamber and a rocker chamber
communicate with each other through an oil delivery passage, and a
push rod chamber and the crank chamber communicate with each other
through an oil chamber and an oil discharge port. Oil mist
generated in the crank chamber flows into the rocker chamber
through the oil delivery passage, as the oil discharge port begins
to resist the flow. The mist flows into the push rod chamber after
the mist is made into liquid for lubrication of parts to be
lubricated. Thus, the oil is returned to the crank chamber from the
oil delivery passage through the rocker chamber, the push rod
chamber, and the oil chamber to form a circulating path.
Accordingly, a larger quantity of oil than the required quantity is
not stored in the rocker chamber, and a preferable amount of
gas-liquid separation may be obtained even when effects caused by
vigorous vertical vibration of a vibrator make the oil stored in
the rocker chamber strongly shake.
Inventors: |
Kurasawa; Ryoji (Tokyo,
JP), Hongo; Shigeatsu (Tokyo, JP), Ishida;
Satoshi (Tokyo, JP), Higuchi; Masaaki (Tokyo,
JP) |
Assignee: |
Fuji Jukogyo Kabushiki Kaisha
(Tokyo, JP)
|
Family
ID: |
19192280 |
Appl.
No.: |
10/350,035 |
Filed: |
January 24, 2003 |
Foreign Application Priority Data
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Jan 31, 2002 [JP] |
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2002-024510 |
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Current U.S.
Class: |
123/572 |
Current CPC
Class: |
F01M
13/04 (20130101); F01M 2013/0444 (20130101) |
Current International
Class: |
F01M
13/04 (20060101); F01M 13/00 (20060101); F01M
013/00 () |
Field of
Search: |
;123/572-574 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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6-6177 |
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Feb 1994 |
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JP |
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10-176518 |
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Jun 1998 |
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JP |
|
Primary Examiner: McMahon; Marguerite
Attorney, Agent or Firm: McGinn & Gibb, PLLC
Claims
What is claimed is:
1. A gas-liquid separation device in a vibrator engine, comprising:
an oil delivery passage through which a crank chamber and a rocker
chamber communicate with each other; an oil return passage through
which said crank chamber and said rocker chamber communicate with
each other; a gas-liquid separation chamber formed in said rocker
chamber, wherein said gas-liquid separation chamber separates
blow-by gas generated in said crank chamber from oil included in
said blow-by gas; a breather device through which said rocker
chamber and an intake system communicate with each other; a first
oil chamber which communicates with a downstream side of said oil
return passage; and an oil discharge port through which said first
oil chamber and said crank member communicate with each other,
wherein a second oil chamber is inserted between said downstream
side of the oil return passage and said first oil chamber.
2. A gas-liquid separation device in a vibrator engine, comprising:
an oil delivery passage through which a crank chamber and a rocker
chamber communicate with each other, wherein said rocker chamber is
formed on a top of a cylinder head; an oil return passage through
which said crank chamber and said rocker chamber communicate with
each other; a gas-liquid separation chamber formed in said rocker
chamber, wherein said gas-liquid separation chamber separates
blow-by gas generated in said crank chamber from oil included in
said blow-by gas; a baffle plate which is inserted between said
rocker chamber and said cylinder head, wherein an inner periphery
of the baffle plate protrudes inwardly from an inner periphery wall
of said cylinder head to form an opening in said baffle plate; a
breather device through which said rocker chamber and an intake
system communicate with each other; an oil chamber which
communicates with a downstream side of said oil return passage; and
an oil discharge port through which said oil chamber and said crank
member communicate with each other.
3. The gas-liquid separation device in a vibrator engine according
to claim 2, wherein a second oil chamber is inserted between said
downstream side of the oil return passage and said oil chamber.
4. The gas-liquid separation device in a vibrator engine according
to claim 2, wherein said rocker chamber includes a plurality of
rocker arms therein, and wherein said opening is formed such that
said plurality of rocker arms are exposed.
5. The gas-liquid separation device in a vibrator engine according
to claim 2, wherein said rocker chamber contains rocker arms
substantially adjacent to said opening.
6. The gas-liquid separation device in a vibrator engine according
to claim 2, wherein said baffle plate is situated between a first
gasket and a second gasket.
7. The gas-liquid separation device in a vibrator engine according
to claim 2, wherein said baffle plate comprises sheet metal.
8. The gas-liquid separation device in a vibrator engine according
to claim 2, wherein said rocker chamber is formed in a rocker
cover, said baffle plate and a pair of gaskets are situated between
an upper end surface of said cylinder head and a lower end surface
of said rocker cover.
9. The gas-liquid separation device in a vibrator engine according
to claim 2, wherein said cylinder head is covered by a gasket, and
wherein said baffle plate comprises an area greater than an area of
said gasket.
10. The gas-liquid separation device in a vibrator engine according
to claim 2, wherein said baffle plate is disposed at a lower
portion of said rocker chamber.
11. The gas-liquid separation device in a vibrator engine according
to claim 2, wherein said oil and said blow-by gas enter said rocker
chamber through said opening so that said oil forms liquid drops in
said rocker chamber.
12. The gas-liquid separation device in a vibrator engine according
to claim 2, wherein said rocker chamber comprises a controllable
volume to adjust said gas-liquid separation chamber.
13. The gas-liquid separation device in a vibrator engine according
to claim 2, wherein said breather device comprises a breather
chamber, said breather chamber communicates with said rocker
chamber through a blow-by passage.
14. A gas-liquid separation device in an engine, comprising: an oil
delivery passage through which a crank chamber and a rocker chamber
communicate with each other, wherein said rocker chamber is formed
on a top of a cylinder head; an oil return passage through which
said crank chamber and said rocker chamber communicate with each
other; a gas-liquid separation chamber formed in said rocker
chamber, wherein said gas-liquid separation chamber separates
blow-by gas generated in said crank chamber from oil included in
said blow-by gas; a baffle plate which is inserted between said
rocker chamber and said cylinder head, wherein an inner periphery
of the baffle plate protrudes inwardly from an inner periphery wall
of said cylinder head to form an opening in said baffle plate; and
a breather device through which said rocker chamber and an intake
system communicate with each other.
15. The gas-liquid separation device in a vibrator engine according
to claim 14, further comprising: an oil chamber which communicates
with a downstream side of said oil return passage.
16. The gas-liquid separation device in a vibrator engine according
to claim 15, wherein a second oil chamber is inserted between said
downstream side of said oil return passage and said oil
chamber.
17. The gas-liquid separation device in a vibrator engine according
to claim 14, wherein said rocker chamber includes a plurality of
rocker arms therein, and wherein said opening is formed such that
said plurality of rocker arms are exposed.
Description
The disclosure of Japanese Patent Application No. 2002-024510 filed
on Jan. 31, 2002 including the specification, drawings and abstract
is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas-liquid separation device,
which efficiently separates an oil mist from blow-by gas flowing
into a rocker chamber, in a vibrator engine.
2. Description of the Related Art
Recently, some overhead valve (OHV) engines have been using a dip
lubrication method by which a stir is provided in a crank chamber
to generate a large amount of oil mist, and the oil mist lubricates
moving parts provided in the crank chamber and a rocker chamber,
and the inner peripheral surface of a cylinder bore. Also, the
above engines have been installed with a breather device in which
blow-by gas filled in the crank chamber is led to an intake system
for re-combustion, using a pulsation generated in the crank
chamber.
However, since a large amount of oil mist is included in the
blow-by gas in the OHV engines adopting the dip lubrication method,
it is required to separate the oil mist from the blow-by gas when
the blow-by gas is led to the breather chamber.
Thereby, in conventional OHV engines adopting the dip lubrication
method, the rocker chamber functions as a gas-liquid separation
chamber, the rocker chamber and the crank chamber communicate with
each other through an oil delivery passage and an oil return
passage, the oil mist which has been directed through the oil
delivery passage is separated from the blow-by gas after the mist
is made into liquid in the rocker chamber, and the separated oil is
returned to the crank chamber through the oil return passage. On
the other hand, the blow-by gas is led to the breather chamber from
which the gas is sent to the intake system for re-combustion, and
gas-liquid separation of the gas is further performed when the gas
flows into the breather chamber.
Here, a general multipurpose engine, which is under a fixed-type
use, has adopted a configuration in which a breather chamber is
provided at one side which is at the downstream side of an oil
return passage and near a crank chamber, for example, as disclosed
in Japanese Utility Patent Publication No. 6-6177.
However, when a breather chamber is provided at the downstream side
of an oil return passage, satisfactory gas-liquid separation may
not be obtained even by vigorous vertical vibration, for example,
in an engine which is installed in a vibrator such as a rammer
(hereinafter referred to as "vibrator engine").
Accordingly, in the vibrator engine, the breather chamber is
provided on the top of a rocker chamber, that is, at a position
which is at the greatest distance from a crank chamber, for
example, as disclosed in Japanese Unexamined Patent Application
Publication No. 10-176518, in order to obtain satisfactory
gas-liquid separation.
However, the technology disclosed in Japanese Unexamined Patent
Application Publication No. 10-176518, in which a large quantity of
oil is returned from the oil return passage to the rocker chamber
by vigorous vertical vibration during operation of the vibrator,
the oil easily remains in the rocker chamber, and it becomes more
difficult to adequately separate oil from the blow-by gas flowing
into the breather chamber, has a disadvantage that the gas-liquid
separation effect is reduced by half.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a gas-liquid
separation device which is installed in a vibrator engine and in
which an amount of oil larger than a required quantity does not
remain in a rocker chamber, and gas-liquid separation can be
adequately performed in the rocker chamber, even when the device is
installed in a vibrator, such as a rammer, with vigorous vertical
vibration.
The present invention is characterized in that an oil chamber
communicates with the downstream side of the oil return passage,
and the oil chamber and the crank chamber communicate with each
other through an oil discharge port, in a gas-liquid separation
device in a vibrator engine, in which a crank chamber and a rocker
chamber communicate with each other through an oil delivery passage
and also through an oil return passage, a gas-liquid separation
chamber, which separates blow-by gas generated in said crank
chamber from oil included in said blow-by gas, is formed in said
rocker chamber, and said rocker chamber and an intake system
communicate with each other through a breather device.
In such a configuration, since at least one oil chamber is inserted
to the downstream side of the oil return passage through which the
rocker chamber and the crank chamber communicate with each other,
and the oil chamber which is located at the most downstream
position and the crank chamber communicate with each other through
the oil discharge port, oil is prevented from flowing from the oil
return passage into the rocker chamber to cause oil flow in one
direction by which the oil is supplied from the oil delivery
passage to the rocker chamber. Then, oil stored in the rocker
chamber is returned to the crank chamber through the oil discharge
port after the oil flows into the oil chamber, passing through the
oil return passage.
The above and other objects, features and advantages of the
invention will become more clearly understood from the following
description by referring to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view of an engine from the front;
FIG. 2 is a longitudinal sectional view of a cylinder block from
the front;
FIG. 3 is a plan view of a cylinder block;
FIG. 4 is a side view of FIG. 2 from the right side;
FIG. 5 is a longitudinal sectional view of a cylinder head, a
rocker cover and a breather device;
FIG. 6 is a plan view of the cylinder head; and
FIG. 7 is a partial sectional view of FIG. 5 from the right
side.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference numeral 1 indicates an OHV (overhead valve) engine which
is installed in a vibrator such as a rammer and comprises: a
cylinder block 2; a cylinder head 3 which is fixed to the top of
the cylinder block 2; and a breather device 5 which is fixed on the
cylinder head 3 through a rocker cover 4.
A crankcase 2a is formed as one body at the lower part of the
cylinder block 2. The crankcase 2a has at one side thereof an
opening which is closed with a crankcase cover 2b to form a crank
chamber 6, and oil is stored in the crank chamber 6. Also, a crank
shaft 6a and a cam shaft 6b are individually provided in the crank
chamber 6 in a transverse manner, and a piston 7 is connected to
the crank shaft 6a through a connecting rod 8.
Reference numeral 9 indicates a scraper which is fixed to the lower
end of the connecting rod 8. When the engine is operated, the
scraper 9 scrapes oil together which is stored in the crank chamber
6 to lubricate parts, such as the inner wall of a cylinder, the
crankshaft 6a, and the cam shaft 6b, which are required to be
lubricated, and to generate oil mist.
Moreover, a rocker chamber 10 formed in the rocker cover 4, and the
crank chamber 6 communicate with each other through an oil delivery
passage 11 passing through the cylinder block 2 and the cylinder
head 3. In addition, a push rod chamber 12 is formed as a
continuous space with the cylinder block 2 and the cylinder head 3,
respectively. The push rod chamber 12 is formed in a bag
configuration by which the rod chamber has an opening to the rocker
chamber 10 at the upper end thereof. Here, the push rod chamber 12
is provided with a function as an oil return passage.
Also, a plurality of push rods 13 are inserted into the push rod
chamber 12, and the lower ends of the push rods 13 are connected,
respectively, to an intake cam and an exhaust cam (both cams are
not shown) formed on the cam shaft 6b through a couple of tappets
14 which are movably supported in the push rod chamber 12.
On the other hand, the upper end of each push rod 13 protrudes into
the rocker chamber 10. The rocker chamber 10 contains a plurality
of rocker arms 16 which are supported by rocker shafts 15, and the
upper end part of each push rod 13 and a stem end of an intake
valve (or an exhaust valve) 18 rest on the both ends of the rocker
arms 16, respectively.
Moreover, as shown in FIG. 6 and FIG. 7, a guide plate 17 guiding
the push rods 13 are fastened and fixed at positions slightly lower
positions of the upper end surface of the cylinder head 3 with nuts
19 which fix the rocker shaft 15.
In addition, a gasket 20, a baffle plate 21 to prevent the oil flow
from, for example, the oil delivery passage 11, and a gasket 22 are
inserted between the upper end surface of the cylinder head 3 and
the lower end surface of the rocker cover 4 in such a manner that
the plate 21 is put on the gasket 20, and the gasket 22 is put on
the plate 21 after the gasket 20 is put on the cylinder head 3.
The baffle plate 21 is of a plate-like member which is made of
sheet metal and the like and, as shown in FIG. 6 and FIG. 7,
secures an area which is larger in comparison with that of the
gasket 20 on the cylinder head 3 to cover the upper end surface of
the cylinder head 3. The inner periphery of the plate 21 protrudes
inward from the inner periphery wall of the cylinder head 3 at the
upper end to form an opening 21a which is formed in such a way that
approximately the all parts of the rocker arm 16 are exposed.
On the other hand, a breather cover 23 forming the breather device
5 is installed on the rocker cover 4 through a gasket 24, and a
breather chamber 25 is formed by enclosing the chamber with the
upper part of the rocker cover 4 and the breather cover 23.
The breather chamber 25 and the rocker chamber 10 communicate with
each other through a blow-by passage 26 opening to the upper part
of the rocker cover 4, and a reed valve 27 which opens and closes
the blow-by gas passage 26 by a change in the pressure difference
between the pressure of the rocker chamber 10 and that of the
breather chamber 25 is disposed on the blow-by gas passage 26 along
the breather chamber 25.
Then, a first oil barrier plate 28 is disposed at a part, which is
above the rocker chamber 10 and communicates with the blow-by gas
passage 26, and, furthermore, a second oil barrier plate 29 is
disposed below the first oil barrier plate 28. The second oil
barrier plate 29 has a larger area than that of the first oil
barrier plate 28, and, as shown in FIG. 5, breathers 30 are formed
between the right and left, in the figure, end surfaces of the
second oil barrier plate 29 and the inner wall of the rocker
chamber 10.
In addition, a return hole 31 to drop oil, which has been made into
liquid in the breather chamber 25, to the rocker chamber 10, is
pierced in the side part of the rocker cover 4, as shown in FIG. 7.
As shown in FIG. 1, a breather pipe 32 to return blow-by gas in the
breather chamber 25 to the intake system is connected to one side
of the breather cover 23.
As shown in FIG. 2, a first oil chamber 33 is formed at one side
slightly above the bottom part of the push rod chamber 12 which is
pierced in the cylinder block 2, and the first oil chamber 33 and
the one side of the bottom of the push rod chamber 12 communicate
with each other through an oil port 34. Here, one side of the first
oil chamber 33 is open to the outside, and the opening is closed
with a cover 35 (refer to FIG. 1), as shown in FIG. 4.
Furthermore, a second oil chamber 37 is formed below the first oil
chamber 33, and both oil chambers 33 and 37 communicate with each
other through an oil port 38. An oil discharge port 39, which
communicates with the crank chamber 6, is pierced in the bottom of
the second oil chamber 37.
Next, the operation of the above configuration according to the
present embodiment will be explained.
When the OHV engine 1 which is installed in a vibrator such as a
rammer is operated, oil stored in the crank chamber 6 is scraped by
the scraper 9 which is fixed at the big end of the connecting rod
8, and, furthermore, parts, such as the inner wall of the cylinder,
the crankshaft 6a, and the cam shaft 6b, which are required to be
lubricated, are lubricated after a large amount of oil mist is
generated by vigorous vertical vibration of the vibrator in the
crank chamber 6 and adheres to the above parts.
Also, the oil mist and the blow-by gas which fill the crank chamber
6 are directed through the oil delivery passage 11, which passes
through the cylinder block 2 and the cylinder head 3, in the
direction to the rocker chamber 10 by pressure fluctuation, which
is caused by reciprocating motion of a piston 7, in the crank
chamber 6.
In such a case, the push rod chamber 12 and the crank chamber 6
communicate with each other through two oil chambers 33 and 37, two
oil ports 34 and 38, and the oil discharge port 39, and the above
ports 34, 38, and 39 become resistant against flow of oil and gas.
Furthermore, it becomes difficult for the oil and the blow-by gas
in the crank chamber 6 to flow from the push rod chamber 12 into
the rocker chamber 10 even when the oil in the crank chamber 6 is
blown off in the direction to the second oil chamber 37 from the
oil discharge port 39, as the above second oil chamber 37 and the
first oil chamber 33 become expansion chambers to buffer oil
blowing-off. Accordingly, most of the oil mist and the blow-by gas
flow into the rocker chamber 10 through the oil delivery passage
11.
Then, most of the oil mist which flows into the rocker chamber 10
through the oil delivery passage 11 is returned into the crank
chamber 6 by the baffle plate 21 disposed at the lower part of the
rocker chamber 10. That is, as a vibrator such as a rammer has been
generally used with some inclination in many cases, it may be
assumed that most of the large amount of oil mist generated in the
crank chamber 6 collides with the wall surface of, for example, the
oil delivery passages 11 to become liquid oil, and the liquid oil
is directed along the above wall surface of the above passage in
the direction to the rocker chamber 10.
As the baffle plate 21 has an opening in which the inner periphery
of the plate 21 protrudes inward from the inner periphery of the
cylinder head 3 at the upper end as shown in FIG. 6 and FIG. 7,
most of the oil mist collides with the lower surface of the baffle
plate 21 to become liquid drops which are returned to the crank
chamber 6, even if the oil adhered to the wall surface of the oil
delivery passage 11, and the oil mist near the wall surface is
directed by the vigorous vertical vibration of the vibrator.
Since the oil mist, and the blow-by gas may be led to the rocker
chamber 10 only from the opening 21a of the baffle plate 21, a
suitable quantity of oil may be supplied to the rocker chamber 10
to prevent excessive supply of oil thereto.
The pressure quickly changes in the rocker chamber 10, and the
blow-by gas and the oil mist repeatedly collide with each other and
with the wall surface of the rocker chamber 10 by the change in the
pressure. Accordingly, most of the oil mist with a larger particle
size than that of the blow-by gas are made into liquid drops, and
only a small amount of the oil mist flows into the breather chamber
25.
In such a case, since a suitable quantity of oil is adjusted to be
supplied at any time to the rocker chamber 10, it is possible to
make the blow-by gas, after preferable gas-liquid separation, flow
into the breather chamber 25 without unnecessary mixing between the
oil and the blow-by gas, even when effects caused by vigorous
vertical movement of the vibrator make the oil stored in the rocker
chamber 10 strongly shake.
In this case, the volume of the rocker chamber 10 may be controlled
to be minimized as the gas-liquid separation chamber, as the baffle
plate 21 prevents in advance a large amount of oil mist from
entering into the rocker chamber 10, and raising of oil from the
push rod chamber 12.
On the other hand, the oil which has been made into liquid in the
rocker chamber 10 lubricates the parts, such as the rocker shaft
15, the rocker arm 16, and the intake valve (or the exhaust valve)
18, which are required to be lubricated and flows in the direction
to the oil delivery passage 11 and the push rod chamber 12. At this
time, as the oil mist and the blow-by gas from the crank chamber 6
are directed to the oil delivery passage 11 to prevent dropping of
the oil, relatively a larger amount of oil drops into the push rod
chamber 12.
Then, the oil which dropped into the push rod chamber 12 is stored
in the bottom of the push rod chamber 12 and flows into the first
oil chamber 33 through the oil port 34 pierced into the side wall
of the chamber 12. The oil stored in the first oil chamber 33 flows
into the second oil chamber 37 through the oil port 38.
Subsequently, the oil stored in the second oil chamber 37 is
returned to the crank chamber 6 through the oil discharge port
39.
Thus, as shown by the arrows shown in FIG. 1, the oil from the
crank chamber 6 flows from the oil delivery passage 11 into the
rocker chamber 10, drops in the direction towards the push rod
chamber 12 from the rocker chamber 10 and is stored in the oil
chambers 33 and 37, and the oil stored in the second oil chamber 37
is returned to the crank chamber 6 through the oil discharge port
39 in such a way that a circulating path is formed. Thus, a larger
quantity of oil than the required quantity is not stored in the
rocker chamber 10, and a preferable amount of gas-liquid separation
may be obtained in the rocker chamber 10.
Here, the oil stored in the oil chambers 33 and 37 is dropped into
the crank chamber 6 by its own weight even when the engine
stops.
Thus, as the oil mist is supplied from the side of the oil delivery
passage 11 to the rocker chamber 10, and the oil which has been
made into liquid in the rocker chamber 10 is dropped mainly from
the side of the push rod chamber 12 to form the circulating path in
the present embodiment, a larger quantity of oil than the required
quantity is not stored in the rocker chamber 10. Thus, a preferable
amount of gas-liquid separation may be obtained without unnecessary
mixing between the oil and the blow-by gas which has flown into the
rocker chamber 10, even when effects caused by vigorous vertical
vibration of the vibrator make the oil stored in the rocker chamber
10 strongly shake.
On the other hand, when the pressure in the rocker chamber 10 is
higher in the breather device 5 than that of the breather chamber
25, the reed valve 27 opens due to the pressure difference. The
blow-by gas bypasses the oil barrier plates 28 and 29 and flows
into the breather chamber 25 through the blow-by gas passage 26.
When the blow-by gas collides with the oil barrier plates 28 and
29, the fine oil mist included in the blow-by gas is made into
liquid for separation.
Then, when the blow-by gas which has flown into the breather
chamber 25 collides with the inner wall of the breather cover 23, a
small amount of the oil mist included in the blow-by gas is further
made into liquid drops, and the blow-by gas after predetermined
gas-liquid separation is led into the intake system through the
breather pipe 32 for re-combustion. Here, the oil which has been
made into liquid drops in the breather chamber 25 is dropped from
the oil return hole 31 (refer to FIG. 7) to the rocker chamber
10.
Moreover, the present invention is not limited to the
above-described embodiment, and, for example, the oil return
passage may be formed in such a way that the passage is independent
of the push rod chamber. Furthermore, the number of oil chambers
may be one, or more than three oil chambers may be formed to
communicate with each other.
Having described the preferred embodiments of the invention
referring to the accompanying drawings, it should be understood
that the present invention is not limited to those precise
embodiments and various changes and modifications thereof could be
made by one skilled in the art without departing from the spirit or
scope of the invention as defined in the appended claims.
As explained above, a preferable amount of gas-liquid separation
may be obtained according to the present invention, while a larger
quantity of oil than the required quantity is not stored in the
rocker chamber, and the volume of the rocker chamber may be
controlled to be minimized even when the device is installed in a
vibrator, such as a rammer, with vigorous vertical vibration.
* * * * *